Refactor gltf loading and triangles attributes

1 files changed, 45 insertions, 0 deletions

diff --git a/shaders/include/math.h b/shaders/include/math.h
new file mode 100644
index 0000000..cc4e2f4
--- /dev/null
+++ b/shaders/include/math.h
@@ -0,0 +1,45 @@
+const float PI = 3.141592653589793f;

+const float TWO_PI = PI * 2.0f;

+

+vec3 less_than(vec3 vec, float value)

+{

+    return vec3(

+        (vec.x < value) ? 1.0f : 0.0f,

+        (vec.y < value) ? 1.0f : 0.0f,

+        (vec.z < value) ? 1.0f : 0.0f);

+}

+

+vec3 sample_hemisphere(vec2 randoms) {

+    float radius  = sqrt(randoms[0]);

+    float theta = 2.0 * PI * randoms[1];

+

+    return vec3(cos(theta) * radius, sin(theta) * radius, sqrt(1 - randoms[0]));

+}

+

+vec2 disk_vec(vec2 randoms) {

+    float z  = randoms[0] * 2.0 - 1.0;

+    float a = 2.0 * PI * randoms[1];

+    float r = sqrt(1.0 - z * z);

+

+    return vec2(cos(a) * r, sin(a) * r);

+}

+

+// Calculates rotation quaternion from axis vector to the vector (0, 0, 1)

+// Input vector must be normalized!

+vec4 rotation_to_z_axis(vec3 axis) {

+    // Handle special case when axis is exact or near opposite of (0, 0, 1)

+    if (axis.z < -0.99999f) return vec4(1.0f, 0.0f, 0.0f, 0.0f);

+

+    return normalize(vec4(axis.y, -axis.x, 0.0f, 1.0f + axis.z));

+}

+

+vec4 invert_rotation(vec4 q) {

+    return vec4(-q.xyz, q.w);

+}

+

+// Optimized point rotation using quaternion

+// Source: https://gamedev.stackexchange.com/questions/28395/rotating-vector3-by-a-quaternion

+vec3 rotate_point(vec4 q, vec3 v) {

+    const vec3 q_axis = q.xyz;

+    return 2.0f * dot(q_axis, v) * q_axis + (q.w * q.w - dot(q_axis, q_axis)) * v + 2.0f * q.w * cross(q_axis, v);

+}